Set the Smart Logic Control in par. 13-00
SL Controller Mode
to ON.
Start/stop command is applied on terminal 18. If stop signal is applied, the adjustable frequency drive will ramp down and go into free mode.
6.1.7 BASIC Cascade Controller
The BASIC Cascade Controller is used for pump applications where a certain pressure (“head”) or level needs to be maintained over a wide dynamic
range. Running a large pump at variable speeds over a wide range is not an ideal solution because of low pump efficiency at lower speeds. In a practical
way, the limit is 25% of the rated full load speed for the pump.
In the BASIC cascade controller, the adjustable frequency drive controls a variable speed (lead) motor as the variable speed pump and can stage up to
two additional constant speed pumps on and off. By varying the speed of the initial pump, variable speed control of the entire system is provided. This
maintains constant pressure while eliminating pressure surges, resulting in reduced system stress and quieter operation in pumping systems.
Fixed Lead Pump
The motors must be of equal size. The BASIC cascade controller allows the adjustable frequency drive to control up to 3 equal size pumps using the
drive's two built-in relays. When the variable pump (lead) is connected directly to the drive, the other 2 pumps are controlled by the two built-in relays.
When lead pump alternations is enabled, pumps are connected to the built-in relays and the drive is capable of operating 2 pumps.
Lead Pump Alternation
The motors must be of equal size. This function makes it possible to cycle the drive between the pumps in the system (maximum of 2 pumps). In this
operation, the run time between pumps is equalized, thus reducing the required pump maintenance and increasing reliability and system lifetime. The
alternation of the lead pump can take place at a command signal or at staging (adding another pump).
VLT
®
AQUA Drive Design Guide 6 Application Examples
MG.20.N5.22 - VLT
®
is a registered Danfoss trademark
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